I've never come across punishments over this or laws hindering it. I don't think it existed. Keep in mind travellers were quite wel prepared during this time, as not just anybody would travel wherever they pleased. A commoner from a rural community might travel to a nearby market town weekly or even daily, but that's about it. They wouldn't need directions in other words.

Travelling tradesmen would however be more prepared in the sense that they could've had guide books or even portolani ("maps" showing the route from port to port or market to market) of some sort. If they were to ask for directions, common sense dictates they ask multiple people... if one person lied you would easily find out.

On the other hand it is also not in your favour whatsoever to lie to a traveller. As prestige is not unimportant in the middle ages, giving your town or locality the reputation of lying to merchants in a way like that could definitely harm future trade.

In general however, I don't think it was very likely for a trader to have to ask. He would most definitely know the general direction in which to go and then figure it out from there. It was also pretty likely for a trader to have been there multiple times already, seeing as they often just went to and fro between places they knew.

There is also an Italian merchants' guidebook from the 12th century that says never to tell someone in the pub which route you will be taking the next day, as that was quite a dangerous thing to do. I think asking for directions carries the same danger.

So to answer your question: I do not think this happened very often, if at all. But feel free to correct me.