I believe Geisy will be so proud with us for discussing about this topic.
Anyway, I somewhat agree to you. I apologize for that.
Geisy's question could be ambiguous. However, when Geisy said "mas de forma positiva", I believe she was talking about "positive and kind way to ask something; without worries; and even without leaving someone worried or angry". She elucidated her question, but she could say "de maneira positiva amorosa, romântica ou uma brincadeira".
When we use the sentence "What about "(a) penny for your thoughts?", we are already suggesting that the listener is worried about financial problems or something which is bothering / troublesome. I should say it is kind of a catty / sarcastic question, which aloofs off and wrecks Geisy's intention.
The keyword here is not aloofness - on the contrary, politeness.
It is just something to ask for someone in order to show how we want to help without being cocky or noisy.
Now, if we consider long-term relationships, of course, there will be no problems to use your suggestion. Jokes are essential for a relationship sometimes.
You should read:https://www.englishexperts.com.br/forum/significado-de-back-a-penny-t51535.htmlhttps://www.englishexperts.com.br/forum/como-dizer-pessoa-folgada-em-ingles-t1141.html
(1) Collins Dictionary.
(2) LOVE, Patricia. STOSNY, Steven. Why Women Talk and Men Walk: How to Improve Your Relationship Without Discussing it
(3) Obscene, Indecent and Profane Broadcasts
. FCC.gov. U.S. Federal Communications Commission. Archived from the original on 2013-12-09. Retrieved 2014-01-20.