SUP Cluster:Error after package import,requiring all servers restart including db server

Hello,

we imported a new package in to SUP and after successfully imported

the

package we have restarted the SUP application servers. but while

login

via mobile through this application package we saw this error :"The package is not deployed or device's protocol version may be incompatible with the server's protocol version. (1>0)

The error could only be gone after we restarted the db server as well. But previously after package import we only needed to restart the application servers (SUP). But now We are puzzled why We had to restart the db servers as well  after the package import. So far everything is working fine but since this is our production , We wanted to know why this happened.

any help will be appreciated

We are using SUP 2.1

Cluster config; 2 Application servers and 1 db server

thanks

Fiston