How much difference can two words have for the meaning?

Dirk had a trial shift for a part time job in a Wagamama restaurant (Dirk’s favourite Japanese style restaurant he used to go in London) last night. He had to seat the people who arrived in the restaurant. He wanted to say: “If you have any questions or problems don´t hesitate to ask.” But instead he said: “If you have any questions or problems don´t ask.” He realised his mistake, got ashamed and walked away and hoped that these guests haven´t realised his mistake.
It seems quite easy to find a job here (especially for Dirk as he has a working holiday visa). The salary is very little but that is something we are very used to;-)!