That does actually happen to the Tama GO and it is quite a normal occurrence. This could just be your tama asking for attention and is a chance for you to either praise or train him/her. Choose correctly and the train bars of your current tama will rise. I wouldn't worry about it too much. There isn't a topic I found of an actual way to predict whether to choose "Praise" or "Train". It's more of a guessing game and doesn't really have any adverse effects for the care of your tamas. The chances of the dialogue bubble appearing is greater with baby tamas.
Below is a comprehensive topic written by Binary about the Tama Go and is very helpful for new Tama GO owners. It's the one I used when I was just starting out. You might also want to check it out.
Click this for more info regarding the Tama GO
I would also just like to give you a heads up because sometimes the tamas would just randomly beep and when you press any button they would just come up to the screen to greet you. This is just the tamas denoting content and happiness so don't worry about it if this happens to you too. This too is also included and is discussed in detail in the above link I gave you. I hope this helps. Enjoy your Tama GO!
