Well, the obvious legal binding and implication is that you cannot go back to the place you were trespassed from. On the issue of the H1B visa, you need to consult with an immigration attorney.
Consult a local WA immigration attorney - many offer free consultations. Can locate attorney on AVVO under the tab "Find a Lawyer" - If need to retain attorney it is worth the price
This is not intended to be legal advise or as legal representation. I am a California personal injury attorney . Be aware that every state has its own statute of limitations; and statutes & case laws that govern the handling of these matters.
As stated in the other answers, you will need to ask immigration attorneys about the impacts on your visa. As for the notice itself, if you return to the store, then you can be arrested for criminal trespass. Stay away from that store.