nst - 35 weeks...babys heart rate high

i go in every week to get a nst...however this week, as soon a sthe monitor was placed on baby’s heart rate was in the 190s. then it dropped to 170s....finally after a few minutes it ranged from 130-175....at first everyone was a bit concerned - two nurses came in and dr came in...they told me to drink some water, but by that point i was stressed and nervous too....they asked if my baby girl was active and she was very active at the time....after about 20 mins, dr came in and told me she is doing ok...she told me her baseline was at 140 and accelerations are a good sign...however, i cant help but wonder why her heart rate is so high and if there is anything else i should be concerned about?? i worry about everything...anyone else experience this??