Playing with bit alot

[pottamus]

I have just started to bring my horse back into walk work after 5 months off because of my back problems. We have been walking out along the lanes a couple of times and I have noticed he is messing with his bit a fair while...chomping on it and generally playing with it. He did not used to do this before his break but now he is all frothed up by the time we are half way round.
He has a loose ring french link and is up to date with dentist checks. He does not appear in pain, just chomping a lot. Any thoughts on why and should I be overly bothered at this early stage?

 

[harrihjc]

I've just posted something very similar, and my horse is also just coming back into work, but he's always been like this. It may just take him a while to get used to it again...

 

[Bossanova]

I'd try raising it up a hole on each side