Second stress test took shorter time. Normal??

I am a 33 year old Diabetic (Diagnosed 2 years ago)
9 months ago I did a stress test. I was very breathless after the test but i did finish.
The goal was to get my heart rate up to 187 in which i did in a little over 12 minutes.
The results of my stress test was inconclusive so the doctor ordered a Cardiolite stress test.
I finally got to do my Cardiolite stress test last week. (9 months later)
I am still waiting for the results.
Again i finished the thread mill test and got my heart rate up to 187.
This time i found the stress test much physically easier. Probably because i have been doing much more exercise in the last year!
However, this time i got my heart rate to 187 a little over a minute sooner.
Does this indicate a potential problem because it didn't take me as long to get HR to 187.
Or is a minute or so in the difference no big deal.

Thanks.