Certainly it would have been better to have covered the roof with a tarp or roofing felt before it rained.
Roof felt rained on.
Osb like all other wood will expand.
Many of the inner components of your roof such as barriers osb boards and felt are also sensitive to water damage and should not be exposed to moisture.
Normal delays and the rain you indicated will not affect the structural properties of the panels.
Roofing felt that has gotten wet can be covered with shingles as long as it is allowed to dry out first the surface underneath did not get wet and it did not wrinkle bubble or rip.
Installing a roof in the rain may void your warranty.
It started raining during the install.
Our osb is rated exposure 1 and that means that it will withstand normal delays in construction.
United roofing gator skin synthetic roof underlayment 42 in x 285 8 ft 1 000 sq ft synthetic roof underlayment.
If the felt.
Good news is that they did a section at a time so the osb was exposed to fairly light rain drizzle for about a half hour before peel and stick membrane was installed.