Straining when urinating?

[rach1stbaby]

Hi,
Bit random, but as a first time mum not sure on some things.
My DD is 3 and half months and shes started making straining type noises when weeing got the last couple of days. A bit like she's going to poo like she's always done but then just wees instead? I've not noticed her doing this before now. I took her to the doctor thinking she might have a UTI but the test came back negative.
I've been told to submit another urine sample and they will send it to the hospital for checks instead as a precaution.
My partner thought her urinating is no longer involuntary and she's aware of it, hence the noises?
Is it normal for her to start making these noises?
Thank you!

My 3.5 year old boy started doing this shortly after training a few months back. It's not every time by any means, just if he was very busy doing something before and us trying to hurry back! I've no concerns.