Does it? Or am I panicking for no reason?

Depends on the game. If the game is GPU intensive, then no. If it requires more CPU, then possibly. The i5 is no slouch, it's a little above midle ground here. So it's hard to say if you're bottlenecking on something without knowing what program you're running and what programs you're running in the background at the time.

What paladin said. If you enjoy GPU dependent settings such as high resolution, texture, AA, shadows etc.. then you don't have to worry.

What is your current GPU?

EVGA GTX 970 FTW ACX 2.0

Ah, right.. I thought you were in the positon to purchase a new one.

Don't worry, it's fine.

so, I can stop crying?

From the benchmarks I've seen the i5 4670k is near the top in most games, so there's not much point of upgrading it right now.

That said, AAA games are moving now towards higher multi-threading, due to the current console architectures (8 cores), so it's likely that future games will perform better on CPU's capable of running more hardware threads.

The i5-4670k is a great CPU and with most games being GPU dependant it will not bottleneck, Relax and happy gaming :D

Yeah, pretty much. It's a decent enough processor.
Depending on the operations, computers can bottleneck in many places. Better is always better, but generally speaking, each component controls itself enough to be its own bottleneck.
Motherboard design or quality may limit overclocking potential of a CPU or RAM beyond the CPU's own speed.
Drive speed and access times may bottleneck loading.
But when it comes to graphics, the card is doing most of its own work without much need for the CPU.
While its possible some games might be non-graphically calculation intensive enough to be limited by your CPU, it seems rather unlikely unless its extremely poorly optimized.

In other words, you're fine!

http://www.tomshardware.com/reviews/gaming-cpu-review-overclock,3106-4.html

Basically, no. You get like 95% of the performance of a i7-4790K, which is negligible.

If you just want a gaming CPU, the highest end i5 is all you need.