I very much doubt it. Try not to become stressed by such things its best for your baby if you have a relaxed pregnancy . good luck and enjoy being pregnant
The odds against you getting Listeria from a sandwich like this are very very small. But if you do come down with flu-like symptoms go and see your doctor and he'll prescribe anti-biotics.
OMG! I was on soft-boiled eggs, mayonnaise and untreated milk from the dairy bulk tank when I was carrying my two. They're both strapping six-footers now, and it doesn't seem to have done them any harm.
It's reasonable to be concerned, but as advised, the chances of any harm to your baby are extremely small.
Your body is very well equipped to protect your baby from conception to birth, and problems from unsuitable food, especially a one-off like this, are so infintesimal as to be ignored.