As long as you make sure the ribs pass the bend test you will be ok!
The mustard doesn't impart a lot of flavor. What it does do is allow for a heavier coating of rub since it forms peaks and valleys for more surface area. If you have a salty rub becareful with putting too much rub.
Post pictures regardless of how they turn out. We enjoy the pron and we can help with any issues you might of come across and the pictures will give us a nice visual of what you experienced.
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