How have the sheds been. Whats the humidity at. I had the same issue. And at two years is when I noticed the problem. Retics are pretty though. What are your temps at as well. The clear bubbles from the mouth I have been told is a sign and unfortuantly I did not know that with my burm and she passed but my retic I did take in and he had a slight case. In fact he has been fighting it for months now, and it on the road to recovery.
It also could have been it just drank water, so it could be nothing. I would keep an eye on it, take it to a vet if you want to know for sure. Keep checking for bubbles. When I use to take my guy out he would bubble from the mouth, or when he was just laying in his cage.
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0.2 Rotts
1.0 Super Tiger
1.0 Amel Retic
0.1 Ball Python
0.1 Red Tail
0.1 Blood Python
1.0 Green Ananconda
1.0 Emerald Tree Boa