Is a heart rate of 146-155 too high when using an elliptical machine?

I am 58 year old woman and exercise regularly. Strength training with a trainer 2x a week, and cardio 3 times a week. I am trying to up my cardio to lose weight. On the elliptical, I have a heart rate between 146 and 155. Is it dangerous to be that high, or is it ok if I am not out of breath? I do this for about 25 min.

Submitted by Betsey from Albany, New York on 01/22/2014