Normally, old people say that if ever you have failed to keep any promise that you have made to any of the God, then they might appear in your dreams to remind you about the offer you have made to them. So think about it, if you have missed anything.
Secondly, many thinks you have Lord Ganesha's blessing up on you and if you are going to face any problems or if you want to tackle any situation, you will definitely go through it. My mother had dreamed Lord Krishna when she was carrying, near to delivery date and in her dreams, Lord Krishna said, don't worry everything will be fine and it was fine and she had a very normal delivery. Even she was also a normal devotee and not a full time devotee and into worshiping Lord Krishna.
Thirdly even though you might not be reciting his mantras for past one
week, the thought about Lord Ganesha will be there in your unconscious mind and
you might be dreaming about the Lord because of that. Also people say that
normally you dream what you have seen during the other times of a day. May be
you have seen a similar idol or picture of Lord Ganesha in the recent days and
that might have been in your inner mind and may be it came out as a dream.
