Anyone have a dog go through a "silent heat?"

We have an 18 month old mini Schnauzer who has gone through two heat cycles (one at 6 months and the other at 12 months). We were anticipating a third this month, but she hasn't shown any of the signs like bleeding.

She did get pretty bloated about a week ago which she did the two previous heat cycles, but that has dissipated.

After a little research it appears some dogs go through this and it is called a silent heat.

How normal is this? We haven't had a female dog in years so this is all new to us.