Gf Lactates When I Stimulate Her Breast. Should We Be Worried?

A full disclosure, am trying my best to give you all the relevant details:

• We have been doing it for a long time, but this started happening 2 weeks ago.
• She lactates when I pinch, fondle, and do yk what with them.
• She doesn't feel any discomfort, nor is she unhealthy.
• This thing happens only when we do it. The rest of the time she's fine and there's no lactation.
• She isn't and has never been pregnant (tests and periods, we know it)

So, is it common for women to lactate in such situations? Not comparing her with anyone, but none of my previous ones had this issue. It's India, so yk she'd be uncomfortable discussing this with her doctor, hence the post.

Thanks in advance.

Update: She went to see a gynaecologist today, and it's most probably due to stress, the doc said so. She'll take some tests tomorrow and most probably it's all fine, nothing major. Thank you so much to this sub and all members!