The logging tag can be at most 23 characters

You can disable it if you so choose.

In Android Studio, Analyze->Inspect Code.

Under Inspection Profile, click on the button with the 3 horizontal dots.

The following window should open. Search for "log" and uncheck "Too Long Log Tags".

Update: Android Studio 2.2, it is located under Android Lint: Correctness

No, it's not a bug.

From Android Studio's Recent Changes on 1.1 Preview 2,

Checks that the tag passed to the logging calls, if its value can be resolved, is at most 23 characters long (as required by the Logging API.)

As shortly explained on the recent changes, it's due to how Log API doesn't allow tag that exceeds 23 characters.

SLF4J Android has an explanation to this:

[...] the length of such tags is currently limited to 23 characters (23 = 32 - 8 for namespace prefix - 1 for C terminator)

which matches the Android's source code.

Currently, the only function that explicitly mentions this exception is Log.isLoggable(),

...

Throws

IllegalArgumentException is thrown if the tag.length() > 23.

However, based on the comments, apparently the logger does throw the exception on release mode (it's ignored in debug mode).

You can disable the lint checking by following Terence's answer, but you've been warned.

You can never ignore this lint check, it definitely could bring unexpected results on your release version since it throws exceptions and stops executing (it would not crash your app).

I have had a terrible lesson learned recently: it's OK on debug mode, but behave differently on release version.

Complementing the answer by @Terence

You can also turn off the specific check via gradle with this in your build.gradle file:

lintOptions {
    disable 'LongLogTag'
}

Or by adding a lint.xml file to your project with xml:

<?xml version="1.0" encoding="UTF-8"?>
<lint>
    <issue id="LongLogTag" severity="ignore" />
</lint>