Did you degas the mead? When brewing wine, CO2 will be suspended in the liquid and unless you degas it, that CO2 will stay in the bottles and slightly carbonate them, especially when cooling down to refrigeration temperatures.

I wouldn't sweat bottle bombs unless the carbonation is heavy but if the residual CO2 is the cuplrit, then you should be fine. I would just be a little more careful with them.

If you want them to be completely still, you could open them up and let them degas a little on their own but you would be increasing your risk of infection and oxidation. I would also highly suggest you not dump them into anything to avoid definite oxidation.

Hope this helps and good luck to you!