This morning the folks at Gmail have reported that they are, indeed, experiencing some difficulties - it's not just you. This is one of those rare instances where it's not just a localized problem in the Gmail universe, there's a real global problem that Google is indeed working on right this minute. As early as 11:30 AM this morning (PST) the Gmail team has had reports of downtime, though at this time it appears that not everyone across the board is seeing the same results.
Google's report on the situation appears to be covering both mobile and web browser iterations of Gmail, the problem being in the system - at the source - rather than in the app for any given device. The service outage appears to have been taking place en-masse over the period of 11:30 until 12:10, but may still be affecting users across the board here and now.
"The problem with Google Mail should be resolved. We apologize for the inconvenience and thank you for your patience and continued support. Please rest assured that system reliability is a top priority at Google, and we are making continuous improvements to make our systems better." - Google, 12:10 PM PST
"We're investigating reports of an issue with Google Mail. We will provide more information shortly." - Google, 11:30 AM PST
This event was colored orange - that meaning for Google that it was a Service Distruption rather than a Service Outage as such. It's rare that you'll ever find Google's mail servers experiencing any sort of trouble, much less an amount worthy of a disruption note like we're seeing today. That is to say: Google's got pretty fabulous servers and a team that works harder than Thor's hammer to keep Gmail available 24 hours a day, all year long.
Have a peek at the Gmail timeline below to gain greater insight on what Gmail has been up to over the past few weeks and what they'll be working on in the near future.