I have been invited to give a seminar related to applying for a postdoctoral position. The professor has been very kind and seems like a very nice person. He also helped me look for a postdoctoral position for my girlfriend. Now I have received the tickets to travel to the university with first class accommodation and luxury amenities. The trip involves international travel and also that I have been talking with other professors to see my best options.
Does this force me to accept the position or is it common that researchers give these nice invitations? Do I need to mention to the professor that I am exploring other options?