Insurance Claim Eligibility For Resigned Employee

I resigned from my previous employer on Nov 4th and relieved on Jan 4th. I have insurance coverage till Jan 4th 2011. I was hospitalised from Dec 26th to Dec 30th and i had claimed insurance for it on Feb 2nd 2011. The insurer is denying my claim saying that i submitted claim after resignation.
Is my claim valid, would i be able to challenge this legally? Please advice.

It is legally valid to be paid unless there is a claim submission timeline that you may have breached.
Regards, Deepak