Hello Rahul
Ah, I see what you mean. This is expected behaviour as you have correctly stated. That timer indicates the amount of time that has gone by since the last update for this particular entry. In other words, it shows how old the information is. Every 30 seconds, RIP does indeed send a new update, so this timer, under normal circumstances, should be reset to zero every 30 seconds. More about this process can be found at the following lesson:
Now a note on terminology. The term flapping is used when something continuously changes (due to a malfunction or due to a bad config). A flapping route is when routing information continues to change in such a way that the next-hop IP continuously changes again and again over time. A flapping interface is one that continuously comes up and goes down over and over again. A flapping interface can cause a flapping route, but a flapping route can also be caused by continuously conflicting routing protocol information. The GRE Tunnel Recursive routing error is a classic case of a flapping route.
Another feature that helps to alleviate flapping in BGP can be found in the following lesson as well.
I may have gone overkill in explaining on this post, but I just wanted to be thorough. 
I hope this has been helpful!
Laz