[PyGame] Text stacking on top of one another

[menator01]

I've been playing around a bit with pygame and image buttons. When creating a button with the button class, I can't seem to get button text correct. It stacks on top of one another in all buttons. Each time I call the class should it not be a new instance of that class? Therefor should not the text be unique to that class. What am I missing here? Thanks for any incite.

import pygame

pygame.init()
pygame.font.init()

# Setup pygame screen
screen_size = (800, 600)
screen = pygame.display.set_mode(screen_size)
pygame.display.set_caption('Pygame Button')

# Setup some colors
screen_bg = 'ivory2'

# Set framerate
fps = 60
framerate = pygame.time.Clock()

# Load and define button images. Three states normal, hover, and pressed
normal = pygame.image.load('normal.png')
hover = pygame.image.load('hover.png')
pressed = pygame.image.load('pressed.png')

# change cursor on hover
hand = pygame.SYSTEM_CURSOR_HAND

# Create Button class
class Button:
    def __init__(self, image, pos, callback, text='Default Text'):
        '''
            Create a animated button from images
            self.callback is for a funtion for the button to do - set to None
        '''
        self.image = image
        self.rect = self.image.get_rect(topleft=pos)
        self.text = text
        self.callback = callback
        self.default()

    def default(self):
        font = pygame.font.SysFont('verdana', 16)
        self.text_surf = font.render(self.text, True, 'cyan')
        self.text_rect = self.text_surf.get_rect()
        # self.text_rect.center = self.rect.center
        self.text_rect.center = (65,20)
        self.image.blit(self.text_surf, self.text_rect.center)


btns = []
col = 100
for i in range(3):
    btns.append(Button(normal, (col, 200), None, text=f'Button {i}'))
    col += 200

# Set a variabe to True and enter loop
running = True
while running:

    # Fill screen with background color
    screen.fill(screen_bg)

    # Start event loop
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    # Get mouse button from pygame
    left, middle, right = pygame.mouse.get_pressed()

    # Blit button to screen
    for btn in btns:
        screen.blit(btn.image, btn.rect)

    # Set framerate and update
    framerate.tick(fps)
    pygame.display.update()