Passenger gem getting updated for Rails app - ruby-on-rails

Question

I have a staging server from my client which has passenger(3.0.5 and 3.0.2) installed on it for an rails app(v=2.3.13), but when I start the server using passenger on the console it's getting updated to 3.0.5-x86_64-ruby1.8.7-linux-gcc4.4.3-1002. In my Gemfile I have mentioned
gem 'passenger', '=3.0.5'
Why is it getting updated?
Thanks in advance.
Here's the log....
when I run the command, **`**RAILS_ENV=staging passenger start**.`**
__________________________________________________________
Nginx core 0.8.54 isn't installed
Phusion Passenger Standalone will automatically install it into:
/var/lib/passenger-standalone/3.0.5-x86_64-ruby1.8.7-linux-gcc4.4.3-1002/nginx-0.8.54
This will only be done once. Please sit back and relax while installation is
in progress.
Checking for required software...
GNU C++ compiler... found at `/usr/bin/g++`
GNU make... found at `/usr/bin/make`
A download tool like 'wget' or 'curl'... found at /usr/bin/wget
Ruby development headers... found
OpenSSL support for Ruby... found
RubyGems... found
Rake... found at `/usr/local/bin/rake`
rack... found
Curl development headers with SSL support... found
OpenSSL development headers... found
Zlib development headers... found
file-tail... found
daemon_controller >= 0.2.5... found
Downloading Passenger binaries for your platform, if available...
Resolving standalone-binaries.modrails.com... 97.107.130.55
Connecting to standalone-binaries.modrails.com|97.107.130.55|:80... connected.
HTTP request sent, awaiting response... 404 Not Found
2013-10-09 08:52:00 ERROR 404: Not Found.
Looks like it's not. But don't worry, the necessary binaries will be compiled from source instead.
Downloading Nginx binaries for your platform, if available...
#
Resolving standalone-binaries.modrails.com... 97.107.130.55
Connecting to standalone-binaries.modrails.com|97.107.130.55|:80... connected.
HTTP request sent, awaiting response... 404 Not Found
2013-10-09 08:52:00 ERROR 404: Not Found.
Looks like it's not. But don't worry, the necessary binaries will be compiled from source instead.
Downloading Nginx...
# wget -O /tmp/root-passenger-standalone-21842/nginx-0.8.54.tar.gz http://nginx.org/download/nginx-0.8.54.tar.gz
--2013-10-09 08:52:00-- http://nginx.org/download/nginx-0.8.54.tar.gz
Resolving nginx.org... 206.251.255.63
Connecting to nginx.org|206.251.255.63|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 650001 (635K) [application/octet-stream]
Saving to: '/tmp/root-passenger-standalone-21842/nginx-0.8.54.tar.gz'
100%
[======================================================================================================>] 650,001 788K/s in 0.8s
2013-10-09 08:52:01 (788 KB/s) - `/tmp/root-passenger-standalone-21842/nginx-0.8.54.tar.gz' saved [650001/650001]
Installing Phusion Passenger Standalone...