Is this a logical fallacy?

When you are going through something hard and wonder where god is, remember that teacher is always quite during a test.

No. There is no argument here. It is a statement of faith (claim). We could say that there is an implied argument:

1) A teacher is always quiet during a test.
2) God is like a teacher.
3) Therefore, God is quiet when he tests you.

Form wise, this is fine. If we evaluate the reasonableness, we can see several issues:

First, a teacher is not always quiet during a test. In fact, many teachers answer questions and provide demonstrable assistance to the student. This would make the conclusion unsound.

Second, this is based on a self-sealing argument : if one feels that God is helping during a "test," then this is evidence that he exists. If one feels God is not there during a test, then he is like a teacher who doesn't help — and this is not evidence against his existence. Another problem with this line of reasoning is inconsistency. When God helps sometimes and other times not, the "God acts in mysterious ways" wildcard is played, which can be used to excuse everything and explain nothing at the same time.

This reminds me of the claim that elephants hide in trees. When the skeptic mentions that nobody has ever seen this before, the retort is "that is because they are extremely good at it!"