Generally, it's a good practice to always specify explicitly whether you want to use the current culture or if the data your processing is culture invariant. The problem is that if you are processing data which is only processed by your software and not presented to the user in any way (for example database identifiers), then you might run into problems if the data is different on different machines.
For example a database identifier may be serialized on a machine with some culture and deserialized on a machine with a different culture, and in that case it might be different! If you specify explicitly that the string you're processing is culture-invariant, then it will always be the same, regardless of what culture is set on the machine.
You can read more about this topic on MSDN code analysis documentation:
CA1305: Specify IFormatProvider