Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
The map app, whichever app it is (-please tell me the name of the map app you are using-), may have to have its settings changed, for instance, so that it gets a GPS position fix periodically at an interval, or repeatedly, so that the map position it shows may be updated. It could be as simple as that, but I don't know what map app you are using, so please let me know, if you need more specific information.
Please tell me what iOS version is on your iPhone... it's necessary for me to give you accurate instructions.
(Tap on Settings, then on General, then on About, and your iOS version should show up.)