Dear LIB readers: Should I collect transport fare from my in-law?

From a male LIB reader. I laughed!

I am an avid reader of your blog and I need advice from LIB house on this issue. I work with a prestigious bank and am OK. I have been dating a girl since January and we are really serious. I have introduced her to my parents and I know hers too, most especially her mom ad sister. Last weekend she took me to her brother's house for introduction, when leaving, her brother gave me transport fare in an envelope which I politely rejected (don't know how much was in the envelop sha). The brother took no harm with the expression on his face. For 3 days after the visit my babe condemned me for not collecting the cash from her brother though it's been settled. But next weekend we are visiting another brother's house, if I am given transport fare again, should I collect?